Biotechnologie Kolloquium: Prof. Katja Bühler (UFZ Leipzig)

Vortragensgast: Prof. Dr. Katja Bühler (UFZ Leipzig)

Titel: Mixed-trophies biofilms driven by Cyanobacteria

Zusammenfassung: The goal of developing alternative production routes with a smaller environmental footprint compared to established processes is driving our projects. In this context, cyanobacteria are highly interesting organisms, as they grow autotrophic, perform oxygenic photosynthesis and many species are capable of fixing atmospheric nitrogen. In Nature, cyanobacteria fulfill a most important role as primary producers in the global food webs. Especially well investigated is their importance in the formation of microbial mats. Microbial mats comprise communities of multiple functional groups of microorganisms embedded in a self-produced, extracellular polymeric matrix. Due to their versatile composition, they represent a self-sustaining, nearly closed ecosystem, which includes the major element cycles and different trophies, and features various models of microbial cooperation.

Despite photo-biocatalysis developing remarkably and the huge potential photoautotrophic microorganisms hold for eco-efficient production scenarios, photo-biotechnology is still in its infancy. A key-challenge in this respect is the low cell-density which cyanobacterial culture typically reach due to light limitation in conventional photobioreactors. Here, we want to present biofilms as an alternative to suspended cell-cultivation formats. In Biofilms, organisms attach to the phase boundaries of solid to liquid or liquid to gaseous. Upon attachment, the organisms change significantly in their cell physiology, and finally start to excrete extracellular substances, which hold the cells in their biofilm architecture and serve as a protection shield. Biofilm growing organisms exhibit a remarkable robustness and very high cell-densities. Coupling different trophies in such biofilms and thereby mimicking the concept of microbial mats, opens up multiple options for biofilm-based catalysis.

Here, we present a first approach to realize this concept, comprising two different species. Cyanobacteria supply oxygen and organic carbon compounds to the biofilm, whereas chemoheterotrophic Pseudomonas sp. is needed as biofilm supporter strain, applied. This work demonstrates prototrophy as a biological strategy for the cultivation of photobiocatalysts in a stable and high cell density format up to 51.8 gBDW L-1, thereby overcoming a key-bottleneck in photo-biotechnology.

The colloquium will take place on Wednesday May 14th at 16:00 in building 15.21, room 2001 (seminar room of the new building). For those that can’t make it in person, you can join online on https://fz-juelich-de.zoom.us/j/7752148866?pwd=bzJacm5acTJvUCtQVTFyMnhzUzdrQT09 (Meeting ID: 775 214 8866 Passcode: PNb7rJ)

[1] Hoschek, A. et al Bioresource Technology. (2019) 282: 171-178